Packaging comprising a breathable valve for perishable products

ABSTRACT

The invention relates to packaging comprising a breathable valve, intended to extend the green life of perishable products. The packaging comprises a flexible container ( 1 ) and a breathable valve assembly ( 2 ) that can be used to control the concentration of oxygen, carbon dioxide, water vapor and ethylene in the atmosphere inside the container, such as to maintain a desired value depending on the weight and the respiration rate of the product. The breathable valve assembly ( 2 ) comprises a ring ( 3 ) and a breathable lid ( 4 ) assembled in order to close the flexible container ( 1 ). The packaging is advantageous over the prior art in that it can be assembled without using any heat-sealing technique and in that it can extend the green life of perishable products, such as fruits and vegetables.

PURPOSE

The present invention relates to the packaging of perishable items suchas vegetables and fruits, in particular to the means for controlling gascomposition in the atmosphere inside the container and facilitatingmanual closure, for instance, of the packing without using automatictechniques such as heat sealing.

DESCRIPTION OF PRIOR ART

Some perishable products, such as vegetables and fruits, continue theirripening and ageing process after being harvested. During ripening andageing, the product undergoes a respiratory process characterized byoxygen absorption and the release of carbon dioxide and ethylene.Additionally, the product transpires moisture, reducing its weight.Decreasing respiration and transpiration in the packaging is critical toextend the green life of perishable products. Another problem associatedwith uncontrolled respiration is reaching a high concentration of carbondioxide in the atmosphere inside the packaging, which can affect theorganoleptic properties of the perishable product.

Prior art includes some alternatives for the control of respiration andtranspiration in packaging perishable products. These technologiesinclude the following: transportation in refrigerated containers;hypobaric packaging, containers with devices that remove ethylene;active packaging that traps oxygen, carbon dioxide, and ethylene;modified atmosphere packaging, coatings on cardboard; direct chemical orphysical treatment on the product; and breathable packaging. Comparedwith breathable packaging, other technologies have some disadvantages,such as the possibility of damage due to low temperatures inrefrigerated alternatives, high costs, consumer perception, anddifficulties in packaging operations.

Breathable packaging is one of the most commonly used packaging forperishable products due to its benefits in terms of costs. Breathablepackaging technology offers various options, including: highpermeability films; macro and microperforated films; permeable patchesand windows; air vents and valves.

Macro and micro perforated films have been disclosed in several patents(U.S. Pat. No. 5,130,152, US2005180664, DE202005011737, GB1106265,GB1134667, GB2141688, and JP6199385). This alternative has somedisadvantages, such as the need to seal the mouth of the packaging, theproduct may block some of the perforations, and the need for additionaloperations in the manufacture of the film or bag.

Permeable patches and windows have been disclosed in prior art (U.S.Pat. No. 4,842,875, U.S. Pat. No. 4,943,440, U.S. Pat. No. 5,045,331,GB1071586, FR2686577, and CN1036539). The main disadvantages of thistechnology are: the need to seal the mouth of the packaging and the needfor additional operations in the manufacture of the film or bag.

Air vents have been disclosed in prior art (US2004131731, US2007257040,US2008116098, WO2007008459, WO2010141467, and JP2002308293). The maindisadvantages of this technology are: the need to seal the mouth of thepackaging and the need for additional operations in the manufacture ofthe bag.

Although some valves have been disclosed in prior art (U.S. Pat. No.3,937,396, U.S. Pat. No. 5,996,800, US2003152296, WO2004108557,WO2004043191, EP0700839, JP1279073, JP11301743, and JP2006125559), allvalves require sealing the bag, as well as additional operations in themanufacturing of the bag.

The packaging of the present invention discloses a combination of aflexible container and a breathable valve, composed in turn by a ringand a breathable lid to extend the green life of perishable products,such as fruits and vegetables. The packaging of the present inventionprovides the possibility of mechanical assembly, either manually orautomatically, without the need of heat-sealing technology or additionaloperations in the manufacture of the bags; it can also be opened andreopened in ripening chambers; it is recyclable and affordable. Inaddition, extending the green life of the product can increase thegrowth period of the fruit or vegetable in the plant.

SUMMARY OF THE INVENTION

The present invention provides a packaging with a breathable valve toextend the green life of perishable products that undergo a respiratoryprocess after being harvested, such as vegetables and fruits. Thepackaging comprises a flexible container and a valve assembly that isassembled in the mouth of the flexible package in order to create acontrolled gaseous atmosphere inside the package. In turn, the valveassembly comprises a ring located outside the flexible container and abreathable lid located inside the flexible container; these twocomponents can be mechanically assembled without the need of heatsealing technologies to close the mouth of the flexible container. Thebreathable lid has fastening means to attach both parts to the middle ofthe flexible container, which can be an interference fit and pressurefittings. The breathable lid can be a plastic cover with multiplemicroperforations or nanoperforations, or an annular section that allowsthe installation of a permeable membrane interspersed among the ring,the flexible container and the breathable lid.

The permeable membrane can be a cavitated, microperforated, ornanoperforated film. The concentration of oxygen, water vapor, carbondioxide, and ethylene is controlled by the permeation of the breathablelid, the weight and respiration rate of the packed perishable product.The permeation of the breathable lid is controlled by the number andsize of micro and nanoperforations, in the case of the plastic cover andthe micro and nanoperforated film; and by gas permeability, in the caseof the cavitated film.

DESCRIPTION OF THE FIGURES

FIG. 1 illustrates a breathable valve (2) assembled and installed in themouth of the flexible container (1). The figure also shows aninterference fit as fastening means and a micro or nanoperforatedplastic cover as breathable lid (4). In this particular embodiment, thebreathable lid (4) has a circular cavity to allow good assembly byinterference with the ring (3).

FIG. 2 illustrates a breathable valve (2) assembled and installed in themouth of the flexible container (1). The figure also shows aninterference fit as fastening means and a micro or nanoperforatedplastic cover as breathable lid (4).

FIG. 3 illustrates a breathable valve (2) assembled, a pressure fitting(6) as fastening means and a micro or nanoperforated plastic cover asbreathable lid (4).

FIG. 4 illustrates a breathable valve (2) assembled, a pressure fitting(6) as fastening means and a micro or nanoperforated plastic cover asbreathable lid (4). The figure also illustrates a rectangular channel(7) to facilitate release without moving parts of the pieces to beassembled by pressure (6).

FIG. 5 illustrates a breathable valve (2) assembled, an interference fit(8) in the ring (3) as fastening means and a micro or nanoperforatedplastic cover as breathable lid (4).

FIG. 6 illustrates another embodiment of the invention using abreathable valve (2) of square shape, an interference fit as fasteningmeans and a micro or nanoperforated plastic cover as breathable lid (4).

FIG. 7 illustrates another embodiment of the invention using abreathable valve (2) of triangular shape, an interference fit asfastening means and a micro or nanoperforated plastic cover asbreathable lid (4).

FIG. 8 illustrates another embodiment of the invention wherein thebreathable lid of the valve assembly is an annular section, allowing theinstallation of a permeable membrane (10) interspersed among the ring(3), the flexible container (1) and the breathable ring (9).

FIG. 9 illustrates the evolution of oxygen and carbon dioxideconcentration over time for two prototypes made in accordance with thepresent invention. It evaluates two microperforated plastic covers with11 and 18 microperforations that range between 250 and 300 microns indiameter.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a packaging fitted with a breathablevalve designed to extend the green life of perishable products thatundergo a respiratory process after being harvested, such as vegetablesand fruits. With reference to the embodiment illustrated in FIGS. 1 and2, the packaging comprises a flexible container (1) characterized by thepresence of at least one mouth, and at least one valve assembly (2)consisting of two parts: a ring (3), located on the periphery and theouter surface of the flexible container's mouth (1), and a breathablelid (4), which mechanically fits to the inner part of the ring (3), suchthat the material of the flexible container's mouth (1) is fastenedbetween the breathable lid (4) and the ring (3).

The flexible container (1) is a flexible film, manufactured for exampleby casting, blowing extrusion, flat film extrusion, coextrusion, orlamination. The polymeric film is manufactured with a polymer preferablyselected from the group comprising polyethylene, polypropylene,polyethylene terephthalate, polyamide, polystyrene copolymers,cellophane, polylactic acid, cellulose acetate, thermoplastic starch andits derivatives, and mixtures thereof.

With reference to FIGS. 3 and 4, the valve assembly (2) comprises twoparts: the ring (3) and the breathable lid (4), which can bemechanically fitted and do not need using heat sealing technologies toclose the flexible container's mouth (1), or additional operations inthe manufacture of the bag. The breathable lid (4) has fastening meansto attach both parts to the flexible container (1) such that the filmthat forms the container's mouth is fixed between the two sides of thevalve. The embodiment illustrated in FIGS. 3 and 4 uses a pressurefitting (6). FIGS. 3 and 4 also illustrate a rectangular channel (7) inthe breathable lid (4) to facilitate release without moving parts of thepieces to be assembled by pressure (6).

With reference to FIGS. 1, 2 and 5, in another embodiment of the presentinvention, the fastening means for attaching both parts of the valveassembly (2) to the flexible container (1) are an interference fit onthe ring (3) and a breathable lid (4). In this sense, it is desirablefor the breathable lid (4) to have tapered sidewalls to facilitateassembly with the ring (3). With reference to FIG. 5, in a particularembodiment of the present invention, the interference fit is producedbetween an extension (8) of the breathable lid (4) and the correspondingcavity in the ring (3). With reference to FIGS. 5 to 7, although thepreferred embodiment is a ring (3) and a breathable plug (4) of circularshape, it is possible to use other shapes, such as triangular orpolygonal.

The ring (3) and breathable lid (4) of the valve assembly (2) may bemanufactured by injection molding or press molding, using a polymerpreferably from the group comprising thermoplastic polyurethane,vulcanized thermoplastic, thermoplastic elastomers, polyethylene,polypropylene, polyethylene terephthalate, polyamide, polystyrenecopolymers, polylactic acid, cellulose acetate, thermoplastic starch andits derivatives, and mixtures thereof. In a particular embodiment of thepresent invention, the ring (3) and breathable lid (4) of the valveassembly (2) are made of a material whose hardness should be less thanthe one that produces a mark on the fruit or vegetable. For example, thehardness for bananas must be less than 80 Shore A for bananas,preferably less than 60 Shore A, in order to ensure that the bananas arenot damaged or dented by the valve. The use of rounded contours isadvantageous for this same reason.

With reference to FIGS. 1 to 7, in another embodiment, the breathablelid (4) can be a plastic cover characterized by multiple micro ornanoperforations (5).

With reference to FIG. 8, another embodiment of the present inventionuses an annular section (9) that allows the installation of a permeablemembrane (10) interspersed among the ring (3), the flexible container(1), and the annular section (9). The permeable membrane (10) can be acavitated, microperforated, or nanoperforated film. The cavitation filmmay be manufactured using a cavitation load such as calcium carbonate.The microperforated film may be manufactured using for examplemechanical, laser, or electrostatic technology. The present inventioncan use any type of breathable lid (4), even with the permeable membrane(10) interspersed between the ring (3) and the flexible container (1).The annular section (9) of this embodiment is mechanically fitted to thering (3) and the flexible container's mouth (1) for tensioning thepermeable membrane (10).

The concentration of oxygen, water vapor, carbon dioxide, and ethylenecan be controlled by the permeation of the breathable lid (4), and theweight and respiration rate of the packed perishable product. Thepermeation of the breathable lid (4) is controlled by the number andsize of micro and nanoperforations, in the case of the plastic cover andthe micro and nanoperforated film, and by gas permeability, in the caseof the cavitated film.

EXAMPLES

The following examples were obtained using a packaging prototypecomprising a breathable valve for perishable products:

Example 1

This example evaluates a packaging prototype of the present inventionhaving the following characteristics: the flexible container is a bagmade of a 30-microns thick polyethylene film with dimensions of 300 by380 mm, a valve assemblage with an internal diameter of 32 mm with aplastic cover with 11 microperforations between 250 and 300 microns.Approximately 1.2 kg of bananas were packed and their green life at roomtemperature and cooled to 13° C. was evaluated. The prototype of thedisclosed packaging was then compared to the following technologiesavailable in the state of the art: a 30-microns thick microperforatedbag with 50 microperforations with a diameter of 200 microns, and a30-microns thick macroperforated bag with 12 perforations with adiameter of 12.5 mm. The packaging comprising a breathable valveincreases green life, decreases weight loss, and reduces the conversionof starch in carbohydrates (measured as degrees Brix).

TABLE 1 Degrees Weight Green Life Brix Loss, % Breathable valve with 11More than 28 12.0 0.49 microperforations between 250 days and 300 microsat room temperature Breathable valve with 11 More than 28 6.0 0.17microperforations between 250 days and 300 micros at 13° C.Microperforated bag with 50 28 days 11.5 0.15 microperforations with adiameter of 200 microns at 13° C. Macroperforated bag with 12 25 days14.5 0.60 perforations with a diameter of 12.5 mm at 13° C.

Example 2

This example evaluates a packaging prototype of the present inventionwith the following characteristics: the flexible container is a bag madeof a 30-microns thick polyethylene film with dimensions of 300 by 380mm, a valve assemblage with an internal diameter of 32 mm with anannular section, and a mechanically microperforated film. Approximately1.2 kg of bananas was packed and their green life cooled to 13° C. wasevaluated. The prototype of the disclosed packaging was compared to thetechnologies available in the state of the art mentioned in Example 1.The packaging comprising a breathable valve increases green life,decreases weight loss, and reduces the conversion of starch incarbohydrates (measured as degrees Brix).

TABLE 2 Degrees Weight Green Life Brix Loss, % Breathable valve with aMore than 28 5.0 0.06 mechanical microperforated film days in theannular section at 13° C. Microperforated bag with 50 28 days 11.5 0.15microperforations with a diameter of 200 microns at 13° C.Macroperforated bag with 12 25 days 14.5 0.60 perforations with adiameter of 12.5 mm at 13° C.

Example 3

This example compares the evolution of oxygen and carbon dioxideconcentration at 13° C. for two plastic covers with 11 and 18perforations. The same flexible container was used, the same valveassembly and the same number of bananas in Example 1. With reference toFIG. 9, after 4 days the concentration of gases becomes regulated to aconstant value that depends on the number of perforations.

Example 4

An important characteristic of the breathable valve's materials is itshardness and contours, in that no damage is caused to the perishableproduct while packing. This example evaluates the effect that thehardness and contours of the material of the packaging comprising abreathable valve has on the bananas. The effect of 3.5 kg (approximatelythree bunches of green bananas) applied to the breathable valve and onthe banana peel was evaluated. Using a Shore A hardness of less than 80and a valve with a rounded contour is essential to prevent the bananapeel from denting.

TABLE 3 Hardness Material Shore A Shore D Surface Result Polyurethane 80Rounded No dents Polyurethane 80 Sharp edges Dents High densitypolyethylene 55 Sharp edges Dents Polypropylene 78 Rounded Dents Rubber62 Rounded No dents

The above methods, figures, and examples are merely illustrative of theinventive concept. Any person skilled in the art will understand thatevident variations and enhancements may be made without departing fromthe inventive concept, which is defined only by the following claims.

1. A breathable packaging intended to extend the green life ofperishable products comprising: a. a flexible container with a mouth;and b. a device that allows the respiration of the perishable product,wherein the device is fastened to the mouth of the container by amechanical coupling.
 2. The packaging of claim 1, wherein the devicethat allows respiration of the perishable product is a breathable valve.3. The packaging of claim 1, wherein the flexible container is apolymeric film.
 4. The packaging of claim 3, wherein the polymeric filmis manufactured with a polymer selected from the group comprisingpolyethylene, polypropylene, polyethylene terephthalate, polyamide,polystyrene copolymers, cellophane, polylactic acid, cellulose acetate,thermoplastic starch and its derivatives, and mixtures thereof.
 5. Thepackaging of claim 2, wherein the breathable valve comprising: a. a ringlocated on the periphery and outer surface of the flexible container'smouth; and b. a breathable lid mechanically coupled to the ring.
 6. Thepackaging of claim 5, wherein the mechanical coupling of the breathablelid to the ring is made using pressure fitting or interference fit. 7.The packaging of claim 6, wherein the breathable lid has tapered annularwalls.
 8. The packaging of claim 5, wherein the breathable lid hasmultiple microperforations or nanoperforations.
 9. The packaging ofclaim 5, wherein the ring and the breathable cap are assembled in suchway that the material of the flexible container's mouth lies between thetwo making part of the mechanical coupling.
 10. The packaging of claim2, wherein the breathable valve comprising: a. a ring located on theouter periphery of the flexible container's mouth; b. an annular sectionmechanically coupled to the ring; and c. a permeable membrane locatedbetween the ring and the annular section, making part of the mechanicalcoupling between the two.
 11. The packaging of claim 6, wherein the ringand the breathable lid are manufactured using a polymer preferablyselected from the group comprising thermoplastic polyurethane,vulcanized thermoplastics, thermoplastic elastomers, polyethylene,polypropylene, polyethylene terephthalate, polyamide, polystyrenecopolymers, polylactic acid, cellulose acetate, thermoplastic starch andits derivatives, and mixtures thereof.
 12. A breathable valve to allowthe respiration of the perishable products stored in a flexiblecontainer, characterized by: a. a ring arranged to be located on theperiphery and outer surface of the flexible container's mouth; and b. abreathable lid arranged to mechanically couple the ring and the flexiblecontainer's mouth.
 13. The valve of claim 12, wherein the ring and thebreathable lid shape is circular.
 14. The valve of claim 12, wherein thebreathable lid has multiple microperforations.
 15. The valve of claim12, wherein the mechanical coupling is made through pressure fit orinterference fitting.
 16. The valve of claim 15, wherein the breathablelid has tapered annular walls.
 17. A breathable valve to allow therespiration of perishable products stored in a flexible container,characterized by: a. a ring arranged to be located on the periphery andouter surface of the flexible container's mouth; b. an annular sectionmechanically coupled to the ring, arranged to receive and fast apermeable membrane, while mechanically coupling to the ring and theflexible container's mouth.